32lt3126 rev · 2020. 3. 10. · connected to create a “one-fail-all-fail” condition. for...

IS32LT3126

Lumissil Microsystems – www.lumissil.com 1 Rev. A, 05/08/2018

150MA DUAL CHANNEL LED DRIVER WITH FAULT DETECTION

May 2018 GENERAL DESCRIPTION The IS32LT3126 is a dual linear programmable current regulator consisting of 2 independently controlled output channels; each channel is capable of sourcing 150mA. Both channels can be combined to provide a total of 300mA. It supports PWM dimming of both channels via power supply modulation (PSM). It also features ENx pins to individually PWM dim and independently adjust the average output current for each channel. The max current for each channel is set with its corresponding external resistor.

The UVx pins set the VCC under voltage lockout of each channel to match the LED stack for high side PWM dimming operation. In addition, the IC integrates fault protection for LED open/short, ISETx pin open/short and over temperature condition for robust operation. Detection of these failures is reported by FAULTB pin. When a fault is detected the device will disable itself and output an open drain low signal. Multiple devices can have their FAULTB pins connected to create a “one-fail-all-fail” condition. For multiple LED string applications, the device can detect a single LED short. The single LED short detection is set by a resistor divider on the STx pins. A single LED short failure is reported by the separate FAULTB_S pin.

The IS32LT3126 is targeted at the automotive market with end applications to include interior and exterior lighting. For 12V automotive applications the low dropout driver can support one to several LEDs on the output channels. It is offered in a small thermally enhanced eTSSOP-16 package.

FEATURES

Dual channel: each channel can source up to 150mA and the two channels combined to source up to 300mA

External resistors individually set source current 4% channel to channel current matching Individually programmable VCC under voltage

lockout to match the LED stack for PSM operation Individual PWM dimming Shared fault flag for multiple devices operation Fault protection with flag reporting:

- Single LED short (optional to turn off all LEDs) - LED string open/short - OUTx pins short to VCC/GND - ISETx pins open/short - Over temperature current rollback (no reporting) - Thermal shutdown

External CSTOR capacitor keeps fault status during start/stop operation

eTSSOP-16 package Operating temperature range from -40°C ~ +125°C AEC-Q100 qualification

APPLICATIONS

Automotive interior/exterior lighting: - Turn signal light

TYPICAL APPLICATION CIRCUIT

Figure 1 Typical Application Circuit

IS32LT3126


Figure 2 Typical Application Circuit (Several Devices In Parallel with FAULTB Interlinkage)

Note 1: For PSM dimming application, high CVCC capacitor value will affect the dimming accuracy. To get better dimming performance, recommend 0.1µF for it.

IS32LT3126


PIN CONFIGURATION

Package Pin Configuration (Top View)

eTSSOP-16

PIN DESCRIPTION

No. Pin Description

1 GND Ground.

2 CSTOR Keep-alive capacitor to maintain the deglitch timer and fault latch status with collapsing VCC.

3 ISET1 Output current setting for channel 1. Connect a resistor between this pin and GND to set the maximum output current.

4 ISET2 Output current setting for channel 2. Connect a resistor between this pin and GND to set the maximum output current.

5 FAULTB_S Open drain fault reporting output with internal pull up to 4.5V. Indicate the fault condition of single LED short.

6 FAULTB Open drain fault reporting output with internal pull up to 4.5V. Indicate the fault conditions except single LED short. This pin is also an input pin. Pulling this pin low will shutdown the device.

7 ST1 LED string voltage monitor pin of OUT1 to achieve single LED short detection.

8 OUT1 Output current source channel 1.

9 OUT2 Output current source channel 2.

10 ST2 LED string voltage monitor pin of OUT2 to achieve single LED short detection.

11 NC Not connect.

12 VCC Power supply input pin.

13 UV1 External under voltage lockout threshold detection pin for OUT1.

14 EN1 Enable pin of OUT1. It can be used to set OUT1 current by PWM. 15 UV2 External under voltage lockout threshold detection pin for OUT2.

16 EN2 Enable pin of OUT2. It can be used to set OUT2 current by PWM.

Thermal Pad Must be electrically connected to GND plane for better thermal dissipation.

IS32LT3126


ORDERING INFORMATION Automotive Range: -40°C to +125°C

Order Part No. Package QTY/Reel

IS32LT3126-ZLA3-TR eTSSOP-16, Lead-free 2500

Copyright © 2018 Lumissil Microsystems. All rights reserved. Lumissil Microsystems reserves the right to make changes to this specification and its products at any time without notice. Lumissil Microsystems assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Lumissil Microsystems does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Lumissil Microsystems receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Lumissil Microsystems is adequately protected under the circumstances

IS32LT3126


ABSOLUTE MAXIMUM RATINGS VCC, OUT1, OUT2, EN1, EN2, UV1, UV2, ST1, ST2 -0.3V ~ +45V ISET1, ISET2, CTSOR, FAULTB, FAULTB_S -0.3V ~ +7.0V Ambient operating temperature, TA=TJ -40°C ~ +125°C Maximum continuous junction temperature, TJ(MAX) +150°C Storage temperature range, TSTG -65°C ~ +150°C Maximum power dissipation, PDMAX 2.15W Package thermal resistance, junction to ambient (4 layer standard test PCB based on JEDEC standard), θJA

46.5°C/W

Package thermal resistance, junction to thermal PAD (4 layer standard test PCB based on JEDEC standard), θJP

1.617°C/W

ESD (HBM) ESD (CDM)

±2kV ±750V

Note 2: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other condition beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS TJ = -40°C ~ +125°C, VCC=12V, the detail refer to each condition description. Typical values are at TJ = 25°C.

Symbol Parameter Conditions Min. Typ. Max. Unit

Power Up Parameter

VCC Supply voltage range 5 42 V

VUVLO VCC under voltage lockout threshold voltage Voltage falling 4.2 4.5 4.8 V

VUVLO_HY VCC under voltage lockout voltage hysteresis 200 mV

ICC VCC supply current VENx= High, RISETx= 20kΩ 3 5.5 mA

ISD Shutdown current in normal mode VENx= Low, TJ= 25°C 1 2 mA

ISD_FLT Shutdown current in fault mode VENx= High, FAULTB= Low TJ= 25°C

1 2 mA

tSD Both of EN pins low time for IC power shutdown 40 48 55 ms

tON EN high time for IC power up IOUT= -150mA, VCC= 12V VENx= High (Note 3)

40 μs

Channel Parameter

VISETx The ISETx voltage 1 V

IOUT Output current per channel (Note 4)

RISETx= 80kΩ, VHR= 1V -27.5 -25 -22.5

mA RISETx= 20kΩ, VHR= 1V -106 -100 -94

RISETx= 13.3kΩ, VHR= 1V -159 -150 -141

VHR Minimum headroom voltage VCC - VOUT, IOUT= -150mA 1100

mV VCC - VOUT, IOUT= -100mA 800

IS32LT3126


ELECTRICAL CHARACTERISTICS (CONTINUE) TJ = -40°C ~ +125°C, VCC=12V, the detail refer to each condition description. Typical values are at TJ = 25°C.

Symbol Parameter Conditions Min. Typ. Max. Unit

IOUT_R Output current per channel range

RISETx= 80kΩ, IOUT=-25mA RISETx= 13.33kΩ, IOUT=-150mA

-150 -25 mA

IOUT_L Output limit current per channel RISETx=5kΩ -290 -230 -170 mA

∆IOUT Current matching RISETx=20kΩ -4 4 %

tSL Current slew time Enable by ENx pin, current rise/fall between 0%~100% 4 μs

ILEAK Leakage current per channel VENx=Low, VOUT=0V, VCC=42V 1 μA

Fault Protect Parameter

tFD Fault deglitch time Fault must be present at least this long to trigger the fault detect 25 μs

VFAULTB FAULTB pin voltage Sink current=20mA 0.2 0.4 V

RFAULTB FAULTB pin internal pull up 210 300 KΩ

VFAULTB_IH FAULTB pin input high enable threshold 2 V

VFAULTB_IL FAULTB pin input low disable threshold 0.8 V

VFAULTB_S FAULTB_S pin voltage Sink current=20mA 0.2 0.4 V

VSCD OUTx pin short to GND threshold Measured at OUTx 1.0 1.2 1.5 V

VSCD_HY OUTx pin short to GND hysteresis Measured at OUTx 220 mV

VOCD OUTx pin open threshold Measured at (VCC-VOUTx) 150 225 300 mV

VOCD_HY OUTx pin open hysteresis Measured at (VCC-VOUTx) 100 mV

ICST CSTOR pin leakage current VCSTOR=5.5V 5 10 μA

TRO Thermal rollback threshold (Note 3) 145 °C

TSD Thermal shutdown threshold (Note 3) 165 °C

THY Over-temperature hysteresis (Note 3) 25 °C

Logic Input

VEN ENx input voltage threshold Voltage rising 1.18 1.23 1.28 V VENHY ENx input hysteresis (Note 3) 40 mV

fPWM PWM frequency to ENx (Note 3) 1 kHz

VUV UVx input voltage threshold Voltage rising 1.18 1.23 1.28 V

VUVHY UVx input hysteresis 40 mV

VST STx input voltage threshold Voltage falling 1.12 1.16 1.20 V

VSTHY STx Input hysteresis 40 mV

RSTPL STx pull up resistor VST=1V 500 kΩ Note 3: Guaranteed by design. Note 4: Output current accuracy is not intended to be guaranteed at output voltages less than 1.5V.

IS32LT3126


TYPICAL PERFORMANCE CHARACTERISTICS

Out

put C

urre

nt (m

A)

Supply Voltage (V)

90

95

100

105

110

5 15 25 35 45

VHR = 2VRISET = 20kΩTJ = -40°C, 25°C, 125°C

Figure 3 IOUT vs. VCC

0

20

40

60

80

100

120

140

160

180

Out

put C

urre

nt (m

A)

Headroom Voltage (V)

0 1 2 3 4 5 6 7 8 9 10

VCC = 12VTJ = 25°C

RISET = 13kΩ

RISET = 20kΩ

RISET = 39kΩ

Figure 5 IOUT vs. VHR

90

92

94

96

98

100

102

104

106

108

110

-40 -25 -10 5 20 35 50 65 80 95 110 125

Out

put C

urre

nt (m

A)

Temperature (°C)

VCC = 12VVHR = 2VRISET = 20kΩ

Figure 7 IOUT vs. TJ

0

20

40

60

80

100

120

140

160

180

Out

put C

urre

nt (m

A)


0 1 2 3 4 5 6 7 8 9 10

VCC = 12VTJ = -40°C

RISET = 13kΩ

RISET = 20kΩ

RISET = 39kΩ


0

20

40

60

80

100

120

140

160

180O

utpu

t Cur

rent

(mA

)


0 1 2 3 4 5 6 7 8 9 10

VCC = 12VTJ = 125°C

RISET = 13kΩ

RISET = 20kΩ

RISET = 39kΩ


200

205

210

215

220

225

230

235

240

245

250

-40 -25 -10 5 20 35 50 65 80 95 110 125

Out

put C

urre

nt (m

A)

Temperature (°C)

VCC = 12VVHR = 2VRISET = 5.1kΩ

Figure 8 IOUT_L vs. TJ

IS32LT3126


0

20

40

60

80

100

120

140

160

180

100 110 120 130 140 150 160 170

Out

put C

urre

nt (m

A)

Temperature (°C)

VCC = 12VVHR = 2V RISET = 13kΩ

RISET = 20kΩ

RISET = 100kΩ

Figure 9 IOUT vs. TA (Thermal Rolloff)

0.5

0.6

0.7

0.8

0.9

1

-40 -25 -10 5 20 35 50 65 80 95 110 125

Supp

ly C

urre

nt (m

A)

Temperature (°C)

VCC = 12VFAULTB = Low

Figure 11 ISD_FLT vs. TJ

0.95

0.96

0.97

0.98

0.99

1.00

1.01

1.02

1.03

1.04

1.05

-40 -25 -10 5 20 35 50 65 80 95 110 125

VIS

ET (V

)

Temperature (°C)

VCC = 12VRISET = 20kΩ

Figure 13 VISET vs. TJ

4.5

4.6

4.7

4.8

4.9

5

5.1

5.2

5.3

5.4

5.5

-40 -25 -10 5 20 35 50 65 80 95 110 125

Supp

ly C

urre

nt (m

A)

Temperature (°C)

VCC = 12VRISET = 20kΩEN = High

Figure 10 ICC vs. TJ

1.00

1.05

1.10

1.15

1.20

1.25

1.30

1.35

1.40

1.45

1.50

-40 -25 -10 5 20 35 50 65 80 95 110 125

Supp

ly C

urre

nt (m

A)

Temperature (°C)

VCC = 12VEN = Low

Figure 12 ISD vs. TJ

1.15

1.17

1.19

1.21

1.23

1.25

-40 -25 -10 5 20 35 50 65 80 95 110 125

VEN

(V)

Temperature (°C)

VCC = 12V VIH

VIL

Figure 14 VEN vs. TJ

IS32LT3126


1.15

1.16

1.17

1.18

1.19

1.2

1.21

1.22

1.23

1.24

1.25

-40 -25 -10 5 20 35 50 65 80 95 110 125

VU

V (V

)

Temperature (°C)

VCC = 12V VIH

VIL

Figure 15 VUV vs. TJ

1.10

1.11

1.12

1.13

1.14

1.15

1.16

1.17

1.18

1.19

1.20

-40 -25 -10 5 20 35 50 65 80 95 110 125

VST

(V)

Temperature (°C)

VCC = 12V

VIH

VIL

Figure 17 VST vs. TJ

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

Out

put C

urre

nt (m

A)

PSM Duty Cycle (%)

VCC = 12VRISET = 20kΩPSM Dimming 500HzTJ = -40°C, 25°C, 125°C

Figure 19 PSM Dimming at 500Hz

4.4

4.45

4.5

4.55

4.6

4.65

4.7

4.75

4.8

-40 -25 -10 5 20 35 50 65 80 95 110 125

VU

VLO

(V)

Temperature (°C)

VCC = 12V

VIH

VIL

Figure 16 VUVLO vs. TJ

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

Out

put C

urre

nt (m

A)

PSM Duty Cycle (%)

VCC = 12VRISET = 20kΩPSM Dimming 1kHzTJ = -40°C, 25°C, 125°C

Figure 18 PSM Dimming at 1kHz

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

Out

put C

urre

nt (m

A)

PSM Duty Cycle (%)

VCC = 12VRISET = 20kΩPSM Dimming 100HzTJ = -40°C, 25°C, 125°C

Figure 20 PSM Dimming at 100Hz

IS32LT3126


0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

Out

put C

urre

nt (m

A)

PWM Duty Cycle (%)

VCC = 12VRISET = 20kΩPWM Dimming 1kHzTJ = -40°C, 25°C, 125°C

Figure 21 PWM Dimming at 1kHz

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

Out

put C

urre

nt (m

A)

PWM Duty Cycle (%)

VCC = 12VRISET = 20kΩPWM Dimming 100HzTJ = -40°C, 25°C, 125°C

Figure 23 PWM Dimming at 100Hz

IOUT50mA/Div

VFAULTB5V/Div

Time (4µs/Div)

VCC = 12VVHR = 2VTJ = 25°C

VEN1V/Div

VISET11V/Div

Figure 25 EN On

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100

Out

put C

urre

nt (m

A)

PWM Duty Cycle (%)

VCC = 12VRISET = 20kΩPWM Dimming 500HzTJ = -40°C, 25°C, 125°C

Figure 22 PWM Dimming at 500Hz

IOUT50mA/Div

VFAULTB5V/Div

Time (4µs/Div)

VCC = 12VVHR = 2VTJ = -40°C

VEN1V/Div

VISET11V/Div

Figure 24 EN On

IOUT50mA/Div

VFAULTB5V/Div

Time (4µs/Div)

VCC = 12VVHR = 2VTJ = 125°C

VEN1V/Div

VISET11V/Div

Figure 26 EN On

IS32LT3126


IOUT50mA/Div

VFAULTB5V/Div

Time (1µs/Div)

VCC = 12VVHR = 2VTJ = -40°CVEN

1V/Div

VISET11V/Div

Figure 27 EN Off

IOUT50mA/Div

VFAULTB5V/Div

Time (1µs/Div)

VCC = 12VVHR = 2VTJ = 125°CVEN

1V/Div

VISET11V/Div

Figure 29 EN Off

IOUT50mA/Div

VISET21V/Div

Time 8ms/Div)


2V/Div

VISET11V/Div

Figure 31 tSD

IOUT50mA/Div

VFAULTB5V/Div

Time (1µs/Div)


1V/Div

VISET11V/Div

Figure 28 EN Off

IOUT50mA/Div

VISET21V/Div

Time 8ms/Div)

VCC = 12VVHR = 2VTJ = -40°CVEN

2V/Div

VISET11V/Div

Figure 30 tSD

IOUT50mA/Div

VISET21V/Div

Time 8ms/Div)


2V/Div

VISET11V/Div

Figure 32 tSD

IS32LT3126


FUNCTIONAL BLOCK DIAGRAM

IS32LT3126


APPLICATION INFORMATION The IS32LT3126 is a 2-channel linear LED current source optimized to drive automotive interior or exterior LED light which can be dimmed via Power Supply Modulation (PSM) or by digitally driving the EN pin.

Each of the 2 output channels is capable of 150mA. The output current is set by two reference resistors (RISETx); one for each channel.

OUTPUT CURRENT SETTING A single resistor (RISETx) controls the maximum output current for each channel. The resistor value for a specific current level is calculated using the following Equation (1):

SETISET I

R 2000 (1)

(13.33kΩ≤RISET≤80kΩ)

RISET need to be chosen 1% accuracy resistor with good temperature characteristic to ensure stable output current.

The device is protected from an output overcurrent condition caused by a too low value RISETx, by internally limiting the maximum current to IOUT_L.

If only one channel is used, the EN pin of the unused channel should be tied to GND to prevent unwanted fault reporting.

POWER SUPPLY MODULATION DIMMING The IS32LT3126 can operate with Power Supply Modulation (PSM) where the device’s power supply is pulse width modulated to achieve LED dimming. The IS32LT3126 stability is not affected by operation with PSM. To get better dimming linearity, the recommended PSM frequency can be in the range of 100Hz to 300Hz, (200Hz Typ.) and input capacitor, CVCC, should be low value (0.1µF Typ.) to ensure rapid discharge during PSM low period.

CSTOR OPERATION To keep the IC operating normally during condition of PSM when VCC goes to zero, CSTOR capacitor provides the keep-alive current needed to power the digital counter and the fault flag circuits. A capacitor value of 2.2µF is recommended. The keep-alive time could be roughly calculated by the following Equation (2):

CST

STORalive I

CVt 5.2 (2)

ENx PINS OPERATION The voltage at the ENx pins must be higher than VEN to enable the channel and below (VEN-VENHY) to disable the channel. The ENx pins of the IS32LT3126 can

accept a PWM signal to implement LED dimming. LED average current may be computed using the following Equation (3).

PWMMAXLED DII (3)

IMAX is computed using Equation (1) and DPWM is the duty cycle. To guarantee a reasonably good dimming effect, recommend PWM frequency in the range of 100Hz ~ 1kHz. Driving the ENx pins with a PWM signal can effectively adjust the LED intensity. The PWM signal voltage levels must meet the ENx pins input voltage levels, VEN. Tie them to VCC pin via a 10KΩ resistor when ENx pins are unused; do not leave them floating.

UVx PINS OPERATION The IC has an internal VCC UVLO set at VUVLO. However, it may be desirable to externally set an UVLO to track the number of LED’s used in the string. For PSM dimming application, the higher UVLO will track the PSM off time to a pre-determined VCC level. In addition, it is necessary to prevent false LED open detection due to the LED string losing its headroom voltage, such as when VCC rises up from zero during power up or PSM dimming. The UVx pin can be used to independently set a VCC under voltage lockout threshold via a resistor divider for each channel.

IS32LT3126

VCC

UVxR1

R2

VBattery

PSM

Figure 33 UVx Pins Operation

This external UVLO threshold voltage can be computed using the following Equation (4):

2

21_ R

RRVV UVUVLOCC

(4)

Any unused UVLO pin must be tied to VCC pin via a 10kΩ resistor; do not leave it floating.

To prevent false open detection, the external UVLO threshold voltage should be set at Equation (5):

OCDMAXLEDUVLOCC VVV __ (5)

Where VLED_MAX is the maximum LED string forward voltage on the output channel.

IS32LT3126


STx PINS OPERATION IS32LT3126 device features single LED short detection using a resistor divider on the STx pins. In the case of any single LED short will result in that the STx pin voltage to drop below the threshold voltage VST and remains for tFD, the FAULTB_S pin pulls low to report the failure to host and all channels continue sourcing current. If FAULTB_S pin is tied to FAULTB pin, the FAULTB_S pin pulls down the FAULTB pin together that turns off the no fault condition channel but keep 4mA sourcing on fault channel for recovery detection. In multiple LEDs per string application, set the detection threshold voltage VDT into below voltage range:

min_max_)1( FDTF VNVVN (6)

Where, N is the number of LEDs in the string. VF_max and VF_min are the maximum and minimum forward voltage of a single LED.

Figure 34 STx Pins Operation

The detection threshold voltage VDT is calculated by the following Equation (7):

2

21

ST

STSTSTDT R

RRVV (7)

If single LED short detection is unused, the unused STx pin should be tied to its corresponding OUTx pin.

OUTPUT STATE DETECTION AND FAULT DIAGNOSTIC IS32LT3126 offers a fault diagnostic function. Output short to GND/VCC, LED string open/short, ISET pins short/open and over temperature shutdown will trigger this function.

An output short to GND or VCC is detected as a fault if the OUTx pin voltage drops below the short detect voltage threshold VSCD or VCC to OUTx drop voltage is lower than VOCD and remains below the threshold for tFD. Then the fault channel will change to source a 4mA current for recovery detection and the other channel will turn off. The FAULTB pin will be pulled low to indicate the fault condition. This state will recover after the fault condition is removed.

Figure 35 OUTx Pins Short Operation

In the event the LED channel is open circuited, the OUTx pin voltage will go up close to VCC. If VCC to OUTx drop voltage remains below the threshold VOCD for tFD, the fault channel will change to source a 4mA current for recovery detection and the another channel will turn off. The FAULTB pin will be pulled low to indicate the fault condition. The state will recover after the open condition is removed.

If the ISETx pin is either short or open, the FAULTB pin will pull low to assert the fault and the both channels will turn off. The state will recover after the fault condition is removed.

FAULTB PARALLEL INTERCONNECTION For LED lighting systems which require the complete lighting system be shut down when a fault is detected, the FAULTB pin can be used in a parallel connection with multiple IS32LT3126 devices as shown in Figure 2. A detected fault output by one device will pull low the FAULTB pins of the other parallel connected devices and simultaneously turn them off. This satisfies the “One-Fail-All-Fail” operating requirement.

THERMAL ROLLBACK OF OUTPUT CURRENT To protect the IC from damage due to high power dissipation, the temperature of the die is monitored. When the temperature of the die is below the thermal rollback start threshold of 145°C (Typ.), the dual output current maximum is the value set by the selection of RISETx. When the die temperature is between the thermal rollback start threshold 145°C (Typ.) and the over temperature shutdown threshold 165°C (Typ.), the output current decreases linearly from the maximum value. During the rollback, the FAULTB pin will not assert this as a fault.

The rollback is related to RISET value:

ISET

JOUTROOUT R

CTKII )145(_

(8)

Where 145°C ≤TJ≤165°C and K=49.

IS32LT3126


THERMAL SHUTDOWN In the event that the die temperature exceeds 165°C, the device will go into shutdown mode. Both channels (OUTx) will turn off. The FAULTB pin will pull low to indicate the fault. At this point, the IC begins to cool off.

Any attempt to enable one or both of the channels back to the source condition before the IC cooled to TJTRO Output current linearly decreases following TJ

High High TJTSD Off Low High TJ

IS32LT3126


Figure 37 Board Via Layout For Thermal Dissipation

IS32LT3126


CLASSIFICATION REFLOW PROFILES

Profile Feature Pb-Free Assembly

Preheat & Soak Temperature min (Tsmin) Temperature max (Tsmax) Time (Tsmin to Tsmax) (ts)

150°C 200°C 60-120 seconds

Average ramp-up rate (Tsmax to Tp) 3°C/second max.

Liquidous temperature (TL) Time at liquidous (tL)

217°C 60-150 seconds

Peak package body temperature (Tp)* Max 260°C

Time (tp)** within 5°C of the specified classification temperature (Tc) Max 30 seconds

Average ramp-down rate (Tp to Tsmax) 6°C/second max.

Time 25°C to peak temperature 8 minutes max.

Figure 38 Classification Profile

IS32LT3126


PACKAGE INFORMATION eTSSOP-16

IS32LT3126


RECOMMENDED LAND PATTERN eTSSOP-16

Note: 1. Land pattern complies to IPC-7351. 2. All dimensions in MM. 3. This document (including dimensions, notes & specs) is a recommendation based on typical circuit board manufacturing parameters. Since land pattern design depends on many factors unknown (eg. user’s board manufacturing specs), user must determine suitability for use.

IS32LT3126


REVISION HISTORY

Revision Detail Information Date

0A Initial release 2017.09.09 0B Update curves and detail description 2018.01.05

A Release to final version 2018.04.10

32lt3126 rev · 2020. 3. 10. · connected to create a “one-fail-all-fail” condition. for...

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